1. Field of the Invention
The present invention relates to an image pickup apparatus having the focus detecting function in a digital camera, a video camera, or the like.
2. Description of the Related Art
As an example of an image pickup element that includes a function element having a specific function in a part of a pixel group that forms the image pickup element, there is a technology to eliminate the use of a dedicated AF sensor by providing a phase difference detecting function of an object image for an image pickup element and to achieve a high-speed phase difference AF.
For example, Japanese Patent Laid-Open No. 2000-292686 provides a pupil divide function by decentering a sensitivity area of a light-receiving part for an optical axis of an on-chip microlens in light-receiving elements (pixel) of part of the image pickup element. These pixels are aligned as focus detection pixels at a predetermined interval in an image pickup pixel group, and thereby a focus detection using a phase difference method is performed
Moreover, there is a technology about a case where there are defective pixels in these focus detection pixel groups.
Japanese Patent Laid-Open No. 2009-163229 discloses a technology to correct a pixel signal of a focus detection pixel with a defect by a pixel signal of a focus detection pixel without defects. Japanese Patent Laid-Open No. 2001-177756 discloses a method of setting a focusing area at a position where there is no defective pixel and which is in a predetermined direction from an area including a defective pixel, when there is the defective pixel in the focusing area.
However, in an image pickup apparatus of the above-mentioned Japanese Patent Laid-Open 2009-163229, a sample pitch becomes rough when, for example, the focus detection pixel is discretely aligned on an image pickup surface, and therefore it is difficult to accurately correct an output of the defective pixel, especially in an object having a high spatial frequency. Further, an image pickup apparatus of Japanese Patent Laid-Open No. 2001-177756 has a problem where a user's desired focusing region may be changed.